It is believed that in an oxide solid-state battery, which uses a solid oxide as an electrolyte, joining the cathode, oxide solid electrolyte layer, and anode by sintering makes it possible to reduce the interface resistance between a cathode and an oxide solid electrolyte layer, the interface resistance between the oxide solid electrolyte layer and an anode, and so on. On the other hand, the interface resistance in a solid-state battery whose layers cannot be joined by sintering such as a sulfide solid-state battery using a sulfide solid electrolyte that is easy to suffer heat deterioration is reduced by pressurizing the battery using a restraining member to increase contact interfaces of battery material in the present circumstances. That is, an advantage of an oxide solid-state battery is that any member for restraining a cathode, oxide solid electrolyte layer, and anode is not necessary, and energy density of a battery as a whole can be easily increased, compared with other types of solid-state batteries.
It is important for producing an oxide solid-state battery to sinter layers. For example, a cathode of an oxide solid-state battery can be composed by sintering a lithium containing composite oxide as a cathode active material. In this point, Patent Literature 1 discloses a method of filling a powder of LiCoO2 which is one of lithium containing composite oxides into a mold, reducing a pressure inside the mold, and applying pressure sintering to the LiCoO2 powder at a temperature from 800° C. to 880° C.